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bgpd: Implement BGP dual-as feature

Browse Source 
This is helpful for migrations, etc.

The neighbor is configured with:

```
router bgp 65000
 neighbor X local-as 65001 no-prepend replace-as dual-as
```

Neighbor X can use either 65000, or 65001 to peer with.

Closes: https://github.com/FRRouting/frr/issues/13928

Signed-off-by: Donatas Abraitis <donatas@opensourcerouting.org>
This commit is contained in:
Donatas Abraitis 2024-09-13 10:51:41 +03:00
parent bf1fa1b2df
commit cadfa693d6
5 changed files with 59 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
bgpd/bgp_packet.c
View File

@ -2702,6 +2702,19 @@ static int bgp_notify_receive(struct peer_connection *connection,
inner.subcode == BGP_NOTIFY_OPEN_UNSUP_PARAM)
UNSET_FLAG(peer->sflags, PEER_STATUS_CAPABILITY_OPEN);
/* Resend the next OPEN message with a global AS number if we received
* a `Bad Peer AS` notification. This is only valid if `dual-as` is
* configured.
*/
if (inner.code == BGP_NOTIFY_OPEN_ERR &&
inner.subcode == BGP_NOTIFY_OPEN_BAD_PEER_AS &&
CHECK_FLAG(peer->flags, PEER_FLAG_DUAL_AS)) {
if (peer->change_local_as != peer->bgp->as)
peer->change_local_as = peer->bgp->as;
else
peer->change_local_as = peer->local_as;
}
/* If Graceful-Restart N-bit (Notification) is exchanged,
* and it's not a Hard Reset, let's retain the routes.
*/

9
bgpd/bgp_updgrp.c
View File

@ -783,8 +783,11 @@ static int update_group_show_walkcb(struct update_group *updgrp, void *arg)
json_updgrp, "replaceLocalAs",
CHECK_FLAG(updgrp->conf->flags,
PEER_FLAG_LOCAL_AS_REPLACE_AS));
json_object_boolean_add(json_updgrp, "dualAs",
CHECK_FLAG(updgrp->conf->flags,
PEER_FLAG_DUAL_AS));
} else {
vty_out(vty, " Local AS %u%s%s\n",
vty_out(vty, " Local AS %u%s%s%s\n",
updgrp->conf->change_local_as,
CHECK_FLAG(updgrp->conf->flags,
PEER_FLAG_LOCAL_AS_NO_PREPEND)
@ -793,6 +796,10 @@ static int update_group_show_walkcb(struct update_group *updgrp, void *arg)
CHECK_FLAG(updgrp->conf->flags,
PEER_FLAG_LOCAL_AS_REPLACE_AS)
? " replace-as"
: "",
CHECK_FLAG(updgrp->conf->flags,
PEER_FLAG_DUAL_AS)
? " dual-as"
: "");
}
}

30
bgpd/bgp_vty.c
View File

@ -5451,7 +5451,7 @@ DEFUN (neighbor_local_as,
return CMD_WARNING_CONFIG_FAILED;
}
ret = peer_local_as_set(peer, as, 0, 0, argv[idx_number]->arg);
ret = peer_local_as_set(peer, as, 0, 0, 0, argv[idx_number]->arg);
return bgp_vty_return(vty, ret);
}
@ -5480,19 +5480,20 @@ DEFUN (neighbor_local_as_no_prepend,
return CMD_WARNING_CONFIG_FAILED;
}
ret = peer_local_as_set(peer, as, 1, 0, argv[idx_number]->arg);
ret = peer_local_as_set(peer, as, 1, 0, 0, argv[idx_number]->arg);
return bgp_vty_return(vty, ret);
}
DEFUN (neighbor_local_as_no_prepend_replace_as,
DEFPY (neighbor_local_as_no_prepend_replace_as,
neighbor_local_as_no_prepend_replace_as_cmd,
"neighbor <A.B.C.D|X:X::X:X|WORD> local-as ASNUM no-prepend replace-as",
"neighbor <A.B.C.D|X:X::X:X|WORD> local-as ASNUM no-prepend replace-as [dual-as$dual_as]",
NEIGHBOR_STR
NEIGHBOR_ADDR_STR2
"Specify a local-as number\n"
"AS number expressed in dotted or plain format used as local AS\n"
"Do not prepend local-as to updates from ebgp peers\n"
"Do not prepend local-as to updates from ibgp peers\n")
"Do not prepend local-as to updates from ibgp peers\n"
"Allow peering with a global AS number or local-as number\n")
{
int idx_peer = 1;
int idx_number = 3;
@ -5510,20 +5511,21 @@ DEFUN (neighbor_local_as_no_prepend_replace_as,
return CMD_WARNING_CONFIG_FAILED;
}
ret = peer_local_as_set(peer, as, 1, 1, argv[idx_number]->arg);
ret = peer_local_as_set(peer, as, 1, 1, dual_as, argv[idx_number]->arg);
return bgp_vty_return(vty, ret);
}
DEFUN (no_neighbor_local_as,
no_neighbor_local_as_cmd,
"no neighbor <A.B.C.D|X:X::X:X|WORD> local-as [ASNUM [no-prepend [replace-as]]]",
"no neighbor <A.B.C.D|X:X::X:X|WORD> local-as [ASNUM [no-prepend [replace-as] [dual-as]]]",
NO_STR
NEIGHBOR_STR
NEIGHBOR_ADDR_STR2
"Specify a local-as number\n"
"AS number expressed in dotted or plain format used as local AS\n"
"Do not prepend local-as to updates from ebgp peers\n"
"Do not prepend local-as to updates from ibgp peers\n")
"Do not prepend local-as to updates from ibgp peers\n"
"Allow peering with a global AS number or local-as number\n")
{
int idx_peer = 2;
struct peer *peer;
@ -14052,6 +14054,10 @@ static void bgp_show_peer(struct vty *vty, struct peer *p, bool use_json,
if (CHECK_FLAG(p->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS))
json_object_boolean_true_add(json_neigh,
"localAsReplaceAs");
json_object_boolean_add(json_neigh, "localAsReplaceAsDualAs",
!!CHECK_FLAG(p->flags,
PEER_FLAG_DUAL_AS));
} else {
if (p->as_type == AS_SPECIFIED ||
CHECK_FLAG(p->as_type, AS_AUTO) ||
@ -14066,13 +14072,15 @@ static void bgp_show_peer(struct vty *vty, struct peer *p, bool use_json,
vty_out(vty, ASN_FORMAT(bgp->asnotation),
p->change_local_as ? &p->change_local_as
: &p->local_as);
vty_out(vty, "%s%s, ",
vty_out(vty, "%s%s%s, ",
CHECK_FLAG(p->flags, PEER_FLAG_LOCAL_AS_NO_PREPEND)
? " no-prepend"
: "",
CHECK_FLAG(p->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS)
? " replace-as"
: "");
: "",
CHECK_FLAG(p->flags, PEER_FLAG_DUAL_AS) ? " dual-as"
: "");
}
/* peer type internal or confed-internal */
if ((p->as == p->local_as) || (CHECK_FLAG(p->as_type, AS_INTERNAL))) {
@ -18664,6 +18672,8 @@ static void bgp_config_write_peer_global(struct vty *vty, struct bgp *bgp,
vty_out(vty, " no-prepend");
if (peergroup_flag_check(peer, PEER_FLAG_LOCAL_AS_REPLACE_AS))
vty_out(vty, " replace-as");
if (peergroup_flag_check(peer, PEER_FLAG_DUAL_AS))
vty_out(vty, " dual-as");
vty_out(vty, "\n");
}

24
bgpd/bgpd.c
View File

@ -4696,6 +4696,7 @@ static const struct peer_flag_action peer_flag_action_list[] = {
{PEER_FLAG_LOCAL_AS, 0, peer_change_reset},
{PEER_FLAG_LOCAL_AS_NO_PREPEND, 0, peer_change_reset},
{PEER_FLAG_LOCAL_AS_REPLACE_AS, 0, peer_change_reset},
{PEER_FLAG_DUAL_AS, 0, peer_change_reset},
{PEER_FLAG_UPDATE_SOURCE, 0, peer_change_none},
{PEER_FLAG_DISABLE_LINK_BW_ENCODING_IEEE, 0, peer_change_none},
{PEER_FLAG_EXTENDED_OPT_PARAMS, 0, peer_change_reset},
@ -6638,9 +6639,9 @@ int peer_allowas_in_unset(struct peer *peer, afi_t afi, safi_t safi)
}
int peer_local_as_set(struct peer *peer, as_t as, bool no_prepend,
bool replace_as, const char *as_str)
bool replace_as, bool dual_as, const char *as_str)
{
bool old_no_prepend, old_replace_as;
bool old_no_prepend, old_replace_as, old_dual_as;
struct bgp *bgp = peer->bgp;
struct peer *member;
struct listnode *node, *nnode;
@ -6653,14 +6654,16 @@ int peer_local_as_set(struct peer *peer, as_t as, bool no_prepend,
!!CHECK_FLAG(peer->flags, PEER_FLAG_LOCAL_AS_NO_PREPEND);
old_replace_as =
!!CHECK_FLAG(peer->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS);
old_dual_as = !!CHECK_FLAG(peer->flags, PEER_FLAG_DUAL_AS);
/* Set flag and configuration on peer. */
peer_flag_set(peer, PEER_FLAG_LOCAL_AS);
peer_flag_modify(peer, PEER_FLAG_LOCAL_AS_NO_PREPEND, no_prepend);
peer_flag_modify(peer, PEER_FLAG_LOCAL_AS_REPLACE_AS, replace_as);
peer_flag_modify(peer, PEER_FLAG_DUAL_AS, dual_as);
if (peer->change_local_as == as && old_no_prepend == no_prepend
&& old_replace_as == replace_as)
if (peer->change_local_as == as && old_no_prepend == no_prepend &&
old_replace_as == replace_as && old_dual_as == dual_as)
return 0;
peer->change_local_as = as;
if (as_str) {
@ -6689,10 +6692,11 @@ int peer_local_as_set(struct peer *peer, as_t as, bool no_prepend,
PEER_FLAG_LOCAL_AS_NO_PREPEND);
old_replace_as = CHECK_FLAG(member->flags,
PEER_FLAG_LOCAL_AS_REPLACE_AS);
if (member->change_local_as == as
&& CHECK_FLAG(member->flags, PEER_FLAG_LOCAL_AS)
&& old_no_prepend == no_prepend
&& old_replace_as == replace_as)
old_dual_as = !!CHECK_FLAG(member->flags, PEER_FLAG_DUAL_AS);
if (member->change_local_as == as &&
CHECK_FLAG(member->flags, PEER_FLAG_LOCAL_AS) &&
old_no_prepend == no_prepend &&
old_replace_as == replace_as && old_dual_as == dual_as)
continue;
/* Set flag and configuration on peer-group member. */
@ -6701,6 +6705,7 @@ int peer_local_as_set(struct peer *peer, as_t as, bool no_prepend,
no_prepend);
COND_FLAG(member->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS,
replace_as);
COND_FLAG(member->flags, PEER_FLAG_DUAL_AS, dual_as);
member->change_local_as = as;
if (as_str)
member->change_local_as_pretty = XSTRDUP(MTYPE_BGP_NAME,
@ -6723,12 +6728,14 @@ int peer_local_as_unset(struct peer *peer)
peer_flag_inherit(peer, PEER_FLAG_LOCAL_AS);
peer_flag_inherit(peer, PEER_FLAG_LOCAL_AS_NO_PREPEND);
peer_flag_inherit(peer, PEER_FLAG_LOCAL_AS_REPLACE_AS);
peer_flag_inherit(peer, PEER_FLAG_DUAL_AS);
PEER_ATTR_INHERIT(peer, peer->group, change_local_as);
} else {
/* Otherwise remove flag and configuration from peer. */
peer_flag_unset(peer, PEER_FLAG_LOCAL_AS);
peer_flag_unset(peer, PEER_FLAG_LOCAL_AS_NO_PREPEND);
peer_flag_unset(peer, PEER_FLAG_LOCAL_AS_REPLACE_AS);
peer_flag_unset(peer, PEER_FLAG_DUAL_AS);
peer->change_local_as = 0;
XFREE(MTYPE_BGP_NAME, peer->change_local_as_pretty);
}
@ -6760,6 +6767,7 @@ int peer_local_as_unset(struct peer *peer)
UNSET_FLAG(member->flags, PEER_FLAG_LOCAL_AS);
UNSET_FLAG(member->flags, PEER_FLAG_LOCAL_AS_NO_PREPEND);
UNSET_FLAG(member->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS);
UNSET_FLAG(member->flags, PEER_FLAG_DUAL_AS);
member->change_local_as = 0;
XFREE(MTYPE_BGP_NAME, member->change_local_as_pretty);
member->last_reset = PEER_DOWN_LOCAL_AS_CHANGE;

3
bgpd/bgpd.h
View File

@ -1507,6 +1507,7 @@ struct peer {
#define PEER_FLAG_CAPABILITY_FQDN (1ULL << 37) /* fqdn capability */
#define PEER_FLAG_AS_LOOP_DETECTION (1ULL << 38) /* as path loop detection */
#define PEER_FLAG_EXTENDED_LINK_BANDWIDTH (1ULL << 39)
#define PEER_FLAG_DUAL_AS (1ULL << 40)
/*
*GR-Disabled mode means unset PEER_FLAG_GRACEFUL_RESTART
@ -2443,7 +2444,7 @@ extern int peer_allowas_in_set(struct peer *, afi_t, safi_t, int, int);
extern int peer_allowas_in_unset(struct peer *, afi_t, safi_t);
extern int peer_local_as_set(struct peer *peer, as_t as, bool no_prepend,
bool replace_as, const char *as_str);
bool replace_as, bool dual_as, const char *as_str);
extern int peer_local_as_unset(struct peer *);
extern int peer_prefix_list_set(struct peer *, afi_t, safi_t, int,